Glioblastoma is the most common primary CNS malignant neoplasm in adults, and accounts for nearly 75% of the cases. Although there has been steady progress in their treatment due to improvements in neuro-imaging, microsurgery, and radiation, glioblastomas remain incurable. The average life expectancy is less than one year from diagnosis, and the five-year survival rate following aggressive therapy, including gross tumor resection, is less than 10%. Glioblastomas cause death due to rapid, aggressive, and infiltrative growth in the brain. The infiltrative growth pattern is responsible for the un-resectable nature of these tumors. Glioblastomas are also relatively resistant to radiation and chemotherapy, and therefore post-treatment recurrence rates are high. In addition, the immune response to the neoplastic cells is mainly ineffective in completely eradicating residual neoplastic cells following resection and radiation therapy.
One problem in treating glioblastoma is the tumor's protection behind the blood-brain tumor barrier (BBTB). A significant obstacle in the development of therapeutics for glioblastoma is the inability of systemic therapies to efficiently cross the BBTB. Saposin C (SapC) is a sphingolipid-activating protein that functions to catabolize glycosphingolipids. SapC-DOPS forms stable nanovesicles which can efficiently cross the blood-brain tumor barrier and fuse with GBM cells inducing cell death.
Rapamycin is a macrolide antibiotic produced by Streptomyces hygroscopicus, which was discovered first for its properties as an antifungal agent. Streptomyces hygroscopicus has also been implicated as a cancer agent.
There remains a need in the art for new therapeutics for the treatment of glioblastoma.